wp-includes/blocks.php:850Determines whether a $post or a string contains a specific block type.
$block_namestring$postint|string|WP_Post|nulloptionalnullboolfunction has_block( $block_name, $post = null ) { if ( ! has_blocks( $post ) ) { return false; } if ( ! is_string( $post ) ) { $wp_post = get_post( $post ); if ( $wp_post instanceof WP_Post ) { $post = $wp_post->post_content; } } /* * Normalize block name to include namespace, if provided as non-namespaced. * This matches behavior for WordPress 5.0.0 - 5.3.0 in matching blocks by * their serialized names. */ if ( ! str_contains( $block_name, '/' ) ) { $block_name = 'core/' . $block_name; } // Test for existence of block by its fully qualified name. $has_block = str_contains( $post, '<!-- wp:' . $block_name . ' ' ); if ( ! $has_block ) { /* * If the given block name would serialize to a different name, test for * existence by the serialized form. */ $serialized_block_name = strip_core_block_namespace( $block_name ); if ( $serialized_block_name !== $block_name ) { $has_block = str_contains( $post, '<!-- wp:' . $serialized_block_name . ' ' ); } } return $has_block;}Introduced in 5.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/blocks.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.